Phenolic hydroxyl-containing compounds, used in adhesives, molding materials, paints, photoresist materials, raw materials for epoxy resins, curing agents for epoxy resins, etc., have also been utilized as the main ingredient of curable resin compositions in various fields of electrical and electronics engineering because of the superior characteristics they exhibit in the cured form, such as superb heat and moisture resistance.
In electrical and electronics engineering, curable compositions are used in, for example, permanent film applications. An example of a permanent film is a coating of a photosensitive resin formed on a component or interposed between components in a semiconductor device such as an IC or an LSI device or a display such as a thin display, and left in the product even after the product is completed. Specific examples of permanent films related to semiconductor devices include solder resists, packaging material, underfill, package bonding layers for circuit devices or other components, and layers for bonding integrated circuit devices to a circuit board. Specific examples of permanent films related to thin displays, typified by LCDs and OELDs, include protective coatings for thin-film transistors, protective coatings for liquid-crystal color filters, black matrix, and spacers.
When a curable composition is used to form permanent films, the composition needs to dissolve well in solvents, and the resulting coatings need to be superior in alkali developability, thermal decomposition resistance, light sensitivity, and resolution. An example of a composition for the production of permanent films is one that contains a novolac phenolic resin obtained through the polymerization of a phenolic hydroxyl-containing compound, such as phenol or naphthol, with an aldehyde (see, for example, PTL 1). However, coatings obtained using the composition disclosed in PTL 1 lack sufficient alkali developability, sensitivity, and resolution.
Another known example of a composition for the production of permanent films is one that contains a phenolic hydroxyl-containing compound that has the cylindrical structure called calixarene. The phenolic hydroxyl-containing compound can specifically be, for example, a naphthol-based calixarene obtained by reacting α-naphthol with formaldehyde in the presence of an alkaline earth metal hydroxide as a catalyst (see, for example, PTL 2). However, the naphthol-based calixarene disclosed in PTL 2 is not sufficiently soluble in organic solvents, and it is difficult to prepare therewith a composition for the production of permanent films.